Solutions of polymers of acrylonitrile



Patented June 16 1953 OFFICE SOLUTIONS OF POLYMERS F ACRYLQNITRILE Joseph B. Dickey, Theodore E. Stanin, W. Coover,'Jr., Rochester, N. Y.,

and Harry assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey 1 No Drawing. Original ap Serial plication A pril. 6, 1948, No. 19,426, now PatentNo. 2,487,859.

Divided and this application January 27, 1949,

Serial N0. 73,234 I This invention relates to new compositions of matter and products prepared therefrom. -More specifically, our invention relates to solutions of polymers of acrylonitrile, such as polyacrylonitrile and copolymers of acrylonitrile containing .at

least 80%acrylonitrile in the polymer. molecule, and to fibers which can be spun fromthese solutions.

Since polymers or acrylonitrile, including both the homopolymersand copolymers thereof, are

6 Claims. (o1. goo -30.

known to possess many desirable chemical and physical properties, such as insolubility in the common organic solvents, including acetone, methanol, ethanol, ethyl ether, ethyl acetate, benzene, toluene, ethylene dichloride, etc, and

insensitivity to these solvents, and unusual tough, ness and moisture regaining properties, many at-,

tempts have been made to find solvents which could be utilized to spin these polymers into fibers. Inorganic salts, such as zinc chloride, lithium bromide and sodium sulfocyanide, have previously been proposed for this purpose, however, fibers spun by extrusion of these-solutions into coagulating bath which are non-solvents for'polyacrylonitrile or, copolymers of acrylonitrile, such as water, dilute acid solutions, glycerol, etc., usually contain large amounts of these salts. The fibers containing these saltsare not uniform and possess poor physical properties. Even where it is possible to eliminate these salts from the fiber, the fibers become weak, spongy or brittle. Some of these salts have the further undesirable property ofcausing the fibers to have a tacky consistency, which results in the individual filaments sticking together to give an extremely brittle, in-

flexible fiber having many of the characteristics of a monofilament. U. S. Patents.2,404,7l3 to 2,404,728 propose to use various'organic compounds as solvents for polymers of acrylonitrile and show how solutions of these polymers can be used to spin fibers which do not possess the undesirable properties that result from the use of inorganic salts.

We have now found that certain organic compounds of phosphorus are useful as solvents for polymers of acrylonitrile, and that these solutions can be used to advantage in the preparation of fibers or films. Itisaccordingly an object of our invention to provide compounds which are useful in dissolving polymers of acryloni'trile. A further object is to provide solutions of polymers of acrye lonitrile which can be advantageously used in the spinning of fibers." A still further object is to provide new organic compounds of phosphorus.

Other objeots will become apparent from a consideration of the following description.

.I-V above are only useful The organic compounds of phosphorus which are useful 1n practicing our invention can be represented by thefollowing four formulas:

wherein R represents a member selected from the group consisting of an alkyl group, such as methyl, ethyl, propyl, isopropyl, etc. (i. el, an alkyl group of the formula CnH21z+1 wherein n is a positive integer from 1 to 3), and an alkenyl group, such as vinyl, propenyl, isopropenyl, etc.

(i. a; an alkenyl group'of the formula cnlizn i wherein n represents a positive integer from 2 to .13). 1 While the compounds represented by Formulas I andII aboveare useful for dissolving bothpolyacrylonitrile and copolymers thereof, the vcompounds represented by Formulas III and for dissolving copolymers of acrylomtrile containing at least 5% of another copolymerizable, unsaturated compound in the polymer molecule.

The compounds represented by Formulas I, III and IV are new compounds and have notheretofore been described in the literature. The compounds represented by Formula II where R is an alkenyl group are described in Hamilton U. S.

Patent 2,382,309, dated August 14, 1945, com-.

pounds where R is a vinyl, propenyl, or isopropeny-l group being disclosed. The following examples will illustrate the manner whereby we prepare the compounds represented by Formulas I, III and IV, and those of Formula II where R is an alkyl. .group. The general methods used below are described by Michaelis in Annalen der Chemiejf Vol. 326 (1903); His. 129 to 258.

Escample I .--Trz's-dimethylaminophosphine oxide M H3 2N13P=0 recovered by distilling the reaction mixture under a vacuum. An almost quantitative yield of dimethylaminodichlorophosphine oxide boiling at 30 to 82 C./18 mm. was obtained.

"lilo convert the dimethylaminodichlorophosphme oxide to the desired tris-dimethylaminophosphine oxide, the above distillate was placed in an autoclave and 270 gms. of anhydrous dimethylamine was added. The charge in the autoclave was heated with agitation at 125 C. for 24 hours. The contents of the autoclave were dissolved in 500 gms. of water, and the water solu-- tion extracted with ether. The ether extract was Example II .-Bis-(dimethylamino) dieting laminophosphine oxide 44.2 gms. of diethylamine hydrochloride were slowly added to 122.8 gms. of phosphorus oxychloride, and the mixture was refluxed for 24 hours or until all the diethylamine hydrochloride had dissolved. The reaction mixture was then distilled under vacuum 'and the excess phosphorus oxychloride removed as a forerun. A yield of 70 gms. of diethylaminodichlorophosphine oxide was obtained as a colorles liquid boiling at 102 to 105 C./17 mm. This product was then placed in an autoclave and 240 gms. of dimethylamine added. The mixture was heated at 125 C. with agitation for 24 hours. The contents of the autoclave were dissolved in 500 gms. of water and the aqueous solution was extracted with ether. After the ether extract had been dried overanhydrous sodium sulfate, the ethereal solution was distilled under vacuum. There were thus obtained, as a colorless liquid,

135 gms. of bis-(dimethylamino)-diethylamino-' phosphine oxide boiling at 68 to 70 C./1 mm.

Example III.-N',N tetmmethylmethanephosphonamidle 15 gms. of ethoxyphosphorusdichloride were dissolved in-60 gms. of substantially anhydrous diethyl ether. This solution was then slowly poured into a stirred solution of 18.5 gms. of anhydrous dimethylamine in 200 gms. of substantially anhydrous diethyl ether at such a rate that a gentle reflux of the ether was maintained throughout the addition. After the two solutions had been intimately mixed, the excess dimethylamine was removed as its hydrochloride by filtering. The diethyl ether was distilled off from the filtrate, and an equal volume of di-n-butyl ether added to the residue. To this solution, 46.8 gins. of methyl iodide dissolved in an equal volume of di-n-butyl ether were added. The mixture of solutions became warm and a white solid began to deposit. The reaction mixture was then heated on a steam bath until most of this white solid had dissolved, and then filtered while still hot. The dinbutyl ether was then removed by distillation under vacuum (20 mm.) Upon distillation of the residue, gms. of N,N-

tetramethylmethanephosphoramide boiling at 63 to 65 C./2 mm. were obtained.

By substituting other alkyl iodides for the .4 v methyl iodide in the above example, still other alkylphosphonamides can be obtained. For'example, when a molecularly equivalent amount of propyl iodide is substituted for the methyl iodide in a molecularly equivalentamount, N,N'- tetramethylpropanephosphonamide having the formula:

can be obtained. This series of reactions can be represented by the following general equations: V

olufioroll +4(CH 3)2NH wherein R. has the'definition set forth above.

- Example IV.--Methoa:y-bis-dimethylaminophosphine oxide '48 gms. of anhydrous methanol were slowly added to 220 gll'lS. of phosphorusoxychloride with stirring, and the mixture was chilled in an ice bath. Carbon dioxide gas was then passed into the reaction mixture until substantially all of the free hydrogen chloride was removed. Upon distillation a good yield of methoxyphosphorusdichloride boiling at 72 to 74 0/49 mm. was obtained.

30 gms. methoxyphosphorusdichloride, obtained as described above, were dissolved in 60 gms. of anhydrous benzene and the solution added dropwise to a stirred solution of 40 gms. of dimethylamine in anhydrous benzene. During the period of addition the reaction mixture was externally cooled by an ice-water bath. The excess of dimethylamine which precipitated as its hydrochloride was filtered OE, and the benzene removed from the filtrate by distillation under vacuum. The residue was distilled under a vacuum, and 24 gms. of methoxy-bis-dimethylaminophosphine oxide were obtained as a colorless liquid boiling at 45 to 46 C./1 mm.

It is well known in the art that by varying the catalyst concentration in a polymerization the average molecular weight of the polymer formed can be controlled. For example, an increase in the catalyst concentration usually causes a reduction in the average molecular weight, while a decrease in catalyst concentration conversely causes an increase in the average molecular weight. The presence of catalyst promoters or activators, such as sulfurous acid and its salts, or chain terminators, such as the alkyl mercaptans, also affect the average molecular weight, so that by a careful choice of polymerization conditions, polymers having intrinsic viscosities from 2 .3 log 71? J t solution t solvent wherein t represents the time in seconds required for a given volume of the. solvent or solution to flow through an orifice, and C represents the concentration of thepolymer expressed in terms-- of per cent. It can thus be seen from the above that the intrinsic viscosity bears a direct relationship to the average molecular weightof the polymer. For the purposes of the present inven;

tion we can advantageously employpolymers or copolymers of acrylonitrile which give a viscosity within the range 2.0 to 5.0 when determined as described above.

-Polymers or copolymers having an .intrinsic viscosity within the range 2.0 to 5.0 can be dissolved in our organic compounds of phosphorus, and the resulting solutions can be conveniently extruded into water, or some other medium in which the polymers are insoluble at room tern-- perature by well known means with the aid of spinnerets. The filaments, upon emerging from the coagulating bath, can be stretched in air,

steam or oil at 100 to 200 C. between two rollers moving at difierent speeds, the second roll having a peripheral speed of from 2 to 8 times that of the first. The filament thus is stretched on the order of 100 to 700% and takes on a high luster and tenacity. Other methods ofspinning which are well known in the art can-be used in, preparing filaments from solutions of polymers of acrylonitrile in our organic compounds of phosphorus. The following examples will illustrate the manner whereby we prepare the polymers of acrylonitrile which are useful in practicing our invention and spin fibers from solutions of these polymers of acrylonitrile in our organic phosphorus compounds.

Example V.-Fz'bers spun from polyacrylonitri'le dissolved in trisdimethylaminophosphine oxide 20 gms. of acrylonitrile, which had been fresh- 1y distilled, were added to 200 cc. of water in which had been dissolved 4 cc. of a 10% solution of hydrogen peroxide. The dispersion thus obtained was placed in a bottle equipped with a, leadlined screw cap, and shaken. The bottle through ahot air chamber heated at 170 C. and

onto a windup drum lmeter in circumference, whichwas rotating at a surface speed of 59.2 feet per minute. After the drum had made 50 revolutions an automatically controlled guide" was shifted 1 inch'to' an adjacent position on the drum and thedrumwas allowed to make another 50 revolutions. This was continued until several such ,50-filament bundles were obtained.

was placed in a water bath and heated for 21 hours at 60 C. (15 0.). At the end of this time a white, powdery precipitate remained in the bottle, and more water was added to the bottle. The white solid was separated from the reaction mixture by filtration, and then transferred to a hot-air oven where it was dried at to C. There were thus obtained 13 gms. of polyacrylonitrile in the form of a white, dry powder. When a sample of this polymer was dissolved in dimethylfformamide and the viscosity I of the solution determined as described above,

it was found to have an intrinsic viscosity of 2.98. 2 gms. of the polyacrylonitrile, prepared as described above, were stirred into 20 cc. of tris dimethylaminophosphine oxide, obtained according to the process of Example I, as a fine powder. The slurry so obtained was then heated at 125 C. on an oil bath, and stirred until a clear solution was obtained. This solution was then spun into fibers by the wet-spinning process according to the following method.

The above clear solution was filtered underpressure into a stainless steel chamber which I Y had a single-hole spinneret, measuring 0.1 mm. in diameter, extending horizontally from the bottom of the chamber in such a manner that upon closed, and the top thereof which was connected These werecut from the drum and the bundles,

containing 50* filaments, each measuring 1 meter in length, were separately twisted to obtain several lmeter lengthsof yarn. The samples thus produced had a fine lustre and a tenacity of 3.5 gms. per denier. The elongation of the fibers was 10%.

Example VI.-Fibers spun from a copolymeroj acrylonitrile. and acrylamidje dissolved indiethylamino-bzs-dimethylaminophosphine oxide Two solutions of freshly purified materials were made up as follows:

Solution] I L 1 Grams V Acrylonitrile 600 Acrylamide a 66.8 Benzoyl peroxide 0.668

' 'Solutz'on II v 1 g Cubic centimeters Acetic acid 500 Dimethylformamide 500 Solution-II was placed in a', 3-necked flask having ground glass "joints and equipped with a mercury-sealed. stirrer, reflux condenser, and

aninlet tube for dry, purified nitrogengas. Onefourth of SolutionI' was slowly added to Solution II with stirring, and the mixture heated at C. until the reaction had started. The reaction was maintained by heating to a temperature of 60 to.80 C., and after the heat of reaction had subsided a second one-quarter portion of Solution I was added. After the heat of reaction had again subsided, the remaining portion of Solution I was'added. The reaction was thus allowed to run for 18 hours, at the end of which time the 3-necked flask was immersed in a water bath heated at60 to C. and allowed to stand for an additional 72 hours. During the total period of reaction, a copolymer of acrylonitrile and acrylamide had precipitated, and this was removed from the reaction mixture by filtration. After washing withcwater and drying in a hot-air oven, heated at 50 to 60 C., a yield of 373 gms. ofcopolymer in the form of a white powder was obtained; When. a sample of the scribed above, it was found to have anintrinsic viscosity of 3.0.

2 gms. of the above copolymer of acrylonitrile Y and acrylamide were finely ground and mixed with .20 cc. of the .diethylamino-bis-dimethylaminophosphine oxide, obtained according to the.

process'described in Example 11. The mixture" was then heated with stirring at 130 C. until a clear solution was obtained. When this solution was spun into fibers according to the process described in Example V above, filaments having a high tenacity and fine appearance'were obtained.-

Ezrample VII -Fz'bers spun from a copolymer of acrylonztrile and acrylamide dissolved in trisdimethylaminophosphine oxide A portion of the copolymer of acrylonitrile and acrylamide prepared as described in Example VI, and having an intrinsic viscosity of 3.0 when dissolved in dimethylformamide as determined by the method described above, was made into a slurry, containing by weight of the polymer, with tris-dimethylaminophosphine oxide. This slurry was then heated at 90 C. with stirring until a clear viscous solution was obtained. When this solution'was spun into fibers in the manner described in Example V above, filaments having good lustre and tenacity were obtained. The polymer solution was also found to be suitable for extrusion into films.

Example VIlL-Fibers spun from polyacrylonitrile dissolved in N,N-tetramethylmetha1iephosphonamide peroxide in dimethyl phthalate, and the mixture 1 heated at 70 C. for an additional 24 hours. After drying of the precipitate, so produced, in'a hotair oven heated at 50 to 60 C.,there were thus obtained an additional 36 gms. of polyacrylonitrile, which with 3'7 gmsjpreviously obtained, gave a total yield of 73 gms. of the polyacrylonitrile. When a sample'of the-polymer so obtained was dissolved in dimethylformamide and the viscosity of the resulting solution measured in accordance with the method set forth above, it was found to have an intrinsic viscosity of 3.15.

2 gms. of polyacrylonitrile, prepared as de-' scribed above, were finely ground and made into a thin slurry with 20 cc. of N,N-tetramethylmethanephosp-honamide, obtained as described in Example III. The slurry was stirred and heated at 90 C., where after a short time it thickened appreciably and cleared to a yellowish viscous dope. This dope was found to be useful for the spinning of fibers according to the process de scribed in Example V. The filaments so obtained had a high tenacity and good lustre.

Example IX.Fz'bers span from a copolymer of acrylom'trile and acrylamide dissolved in methox'y-bz's-dimethylamlnophosphine oxide 18 gms. of freshly distilled acrylonitrile were mixed with 2 gms. of freshly distilled acrylamide and the mixture dissolved in 30 cc. of a mixture of equal parts of acetic acid and dimethylformamide. After addition of 20 mg. of benzoyl peroxide, the solution was heated at 70 C. on a water bath for 19 hours. During the polymerization some copolymer of acrylonitrile and acrylamide had precipitated. The reaction mixturewas then milled into acetone where the polymer was'completelyi precipitated; After separation of the polymerby filtration, it" was washed with more acetoneand finally dried in a hot-air oven heated at 50'to 60 C. There were thus obtained 13.4 gms. of a copolymer of acrylonitrile and acrylamide When a sample of this copolymer was dissolved'in dimethylformamide and the viscosity of the resulting solution measured in the manner described above, it was found to have an intrinsic viscosity of 3.74.

2.2 gms. of the above copolymer were finely ground, were dispersed in 20 cc. of methoxy-bisdimethylaminophosphine oxide, and the resulting slurry heated at 90 C. with stirring until a clear, viscous solution was-obtained. When this solution was spun into fibers according to the process described in Example V above, filaments having good lustre and excellent tenacity and elongation were obtained.

Example X.Fibers spun from a copolymer of acrylonitrile and acrylamide dissdlved in N,N'- tctmmethylisopropenylphosphonamidc 2 gms. of the polymer of acrylonitrile and acrylamide prepared in Example IX above were finely ground and dispersed in 20 cc. of N,N'- tetramethylisopropenylphosphonamide, obtained as described in Hamilton U. S. Patent 2,382,309. The slurry so obtained was heated on an oil bath at 160 C. with stirring until a clear, viscous solution had been obtained. This solution remained clear on cooling to room temperature and was found to be. useful for spinning into fibers according to the process described in Example V. The filaments thus obtained were lustrous and had good tenacity. This solution was also found to be useful for extrusion into films.

Example XI.FibBTS spun from a, copolymer of acrylonltrile and N-(B,B-dlfluoroethyl) acrylamide dissolved in N,N'-tetmmethylmethancphosphonamide acrylonitrile were dissolved in 15 cc. of a solvent made by mixing equal volumes of acetic acid and dimethylformamide. were added and the mixture heated at 50 to 60 C. for 24 hours. There was thus obtained a powdery polymer which was separated from the reaction mixture by filtration, after which it was washed with alcohol. ter drying in a hot-air oven at 50 to 60 C., '7 gms. of copolymer were obtained. Upon analysis this copolymer was found to contain 20.5% of N-(,8,;9-difluoroethyl) acrylamide in the polymer molecule.

2 gms. of the above copolymer were finely ground and dispersed in 20 cc. of N,N'-tetramethylmethanephosphonamide. The dispersion was then heated at 90 C. with stirring for a short time until it became clear and viscous. When fibers were spun from this viscous dope according to the process described in Example V, dull, weak filaments were formed. When these filaments were stretched 500% in air heated at 180 7 C., they became strong, lustrous and elastic.

While our invention as described above is most advantageously applied to the preparation of solution of polyacrylonitrile, or copolymer of acrylonitrile with acrylamides, it is understood that solutions of copolymers or interpolymers of acrylonitrile with other simple, copolymerizable, unsaturated compounds can be prepared according l0 mgs. of benzoyl peroxide to the processes described herein. Typical copolymerizable unsaturated compounds include vinyl acetate, vinyl chloride, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl a'crylate, a-methyl-acrylic acid, methyl a-methylacrylate, ethyl a-methylacrylate, propyl a-methylacrylate, acrylamide, a-methylacrylamide, styrene, ethylene, propylene, isobutylene, etc. While I our organic phosphorus compounds can be used .for copolym'ers containing from 80 to 95% of acrylonitrile in the polymer molecule.

Solutions of our polymers of acrylonitrile can also be cast in the form of films by passage from a hopper onto a rotating metallic surface under the smoothing action of a doctor knife. The sol vent can be removed by any of the means known to art, as for example, by the wet method utilizing a liquid bath containing a non-solvent for the polymer. Molded articles can also be prepared by using our solutions of copolymers, or lacquers, coating materials, etc., can be prepared therefrom.

Thi application is a division of our application S. N. 19,426 filed April 6, 1948, now U. S. Patent 2,487,859, dated November 15, 1949.

What we claim and desire secured by Letters Patent of the United States is:

1. As a new composition of matter, a copolymer of acrylonitrile containing in the polymer molecule from 80 to 95% by weight of 'acrylonitrile and from to 20% by weight of another monoethylenically-unsaturated, polymerizable compound dissolved in an organic phosphorus compound selected from the group consisting of those represented by the following two formulas:

2. As a new composition of matter, a copolymer of acrylonitrile containing in the polymer molecule from 80 to 95% by weight of acrylonitrile and from 5 to 20% by weight of another monoethylenically-unsaturated, polymerizable compound dissolved in an organic phosphorus compound having the formula:

3. As a new composition of matter, a copoly- I mer of acrylonitrile containing in the polymer molecule from 80 to 95% by weight of acrylonitrile and from 5 to 20% by weight of another monoethylenically-unsaturated, polymerizable compound dissolved in an organic phosphorus compound having the formula:

4. As a new composition of matter, a copolymer of acrylonitrile and acrylamide, containing in the polymer molecule from to acrylonitrile and from 5 to 20% of acrylamide, dissolved in an organic phosphorus compound selected from the group consisting of those represented by the following two formulas:

5. As a new composition of matter, a copolymer of a'crylonitrile and acrylamide, containing in the polymer molecule from 80 to 95% acrylonitrile and from 5 to 20% of acrylamide, dissolved in an organic phosphorus compound having the formula:

6 onao-rmwnmh 6. As a new composition of matter, a copolymer of acrylonitrile and acrylamide, containing in the polymer molecule from 80 to 95% acrylonitrile and from 5 to 20% of acrylamide, dissolved in an organic phosphorus compound having the formula:

JOSEPH B. DICKEY. THEODORE E. STANIN. HARRY W. C'OOVER, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 7 2,172,241 Dickey et al. Sept. 5, 1939 2,456,360 Arnold Dec. 14, 1948 

1. AS A NEW COMPOSITION OF MATTER, A COPOLYMER OF ACRYLONITRILE CONTAINING IN THE POLYMER MOLECULE FROM 80 TO 95% BY WEIGHT OF ACRYLONITRILE AND FROM 5 TO 20% BY WEIGHT OF ANOTHER MONOETHYLENICALLY-UNSATURATED, POLYMERIZABLE COMPOUND DISSOLVED IN AN ORGANIC PHOSPHORUS COMPOUND SELECTED FROM THE GROUP CONSISTING OF THOSE REPRESENTED BY THE FOLLOWING TWO FORMULAS: 